ADI-FDTD在激励源和完纯导体边界处的精确格式

证明了当采用交替方向隐式时域有限差分法(AD I-FDTD)计算时,完纯导体和激励源处的算法格式与无源空间的算法格式不同,并推导了AD I-FDTD算法在源和完纯导体所在网格处的精确格式。利用常规的FDTD、无源空间的AD I-FDTD以及在源和导体处采用精确格式的AD I-FDTD,分别计算了点源激励的在自由空间传播的二维TE波、TM波垂直入射于金属条带FSS的散射场。计算结果表明,如果计算域中包含导体或激励源,直接采用通常的AD I-FDTD格式会带来很大的计算误差,而采用该精确格式后,计算结果与FDTD的计算结果吻合,从而证明了本文导出的AD I-FDTD在导体和激励源处的精确格式的正确性和使用的必要性。

Accurate Algorithm on Source and Perfect Conductor Boundary for ADI-FDTD

The algorithm on source and perfect conductor boundary is proved to be different from the algorithm in source-free space in the alternating-direction implicit-finite-difference time-domain(ADI-FDTD) calculation,and the accurate algorithm on source and perfect conductor cells for ADI-FDTD is derived.TE wave propagation in 2-D free space and the scattered field from 2-D frequency selective surface(FSS) formed by infinite-periodic strip grating are simulated using tradition FDTD,ADI-FDTD in source-free space and ADI-FDTD with the accurate algorithm on source and perfect conductor boundary,respectively.It is found that serious calculation errors occur when there have the source and the conductor in the computational domain and use traditional ADI-FDTD.Numerical results of ADI-FDTD with the accurate algorithm agree well with those of traditional FDTD.The validity and the necessity of the accurate algorithm on source and perfect conductor cells for ADI-FDTD are proved.